We plan to identify the divalent metal binding sites of yeast enolase by using the covalent character of chromicocomplexes as an "affinity label" so that peptide fragments containing the liganding groups may be obtained and sequenced. The technique will be applied to a variety of more complex metal binding systems subsequently. Human erythrocyte pyruvate kinase is to be suited in detail with respect to possible control by phosphorylation and oxidation. We will also examine its potential to catalyze the glycolate kinase reaction which may have relevance in this cell type. We will examine the interrelationship of allosteric affectors, configurational changes and covalent modifications to define as completely as possible the network of controls that operate on this enzyme.